Non-deterministic gettext behavior in PHP

Question

I am using gettext in PHP and I have very strange problem. When I keep reloading the page, the strings are not translated to English most of the time , but sometimes they are!!!

My code goes like this (it is part of bigger code though):

bindtextdomain ('messages', dirname(__FILE__) . '/lang/nocache'); # https://stackoverflow.com/a/13629035 (nevim jestli je to u me problem, ale pro jistotu
bindtextdomain ('messages', dirname(__FILE__) . '/lang');
textdomain('messages');
bind_textdomain_codeset('messages', 'UTF-8');

$rv = setlocale(LC_MESSAGES, 'en_US.UTF-8');
var_dump($rv); # always returns "en_US.UTF-8"

echo "<br>TEST: " . _("Úvod");
echo "<br>TEST: " . _("Výsledky");
echo "<br>TEST: " . gettext("Úvod");

When I just cut this code snippet to a separate PHP file, the text always gets translated. I don't suspect my bigger code though of producing this non-determinism, since this piece of code inside is compact and not affected by other parts. I suspect that this strange non-determinism only appears under certain conditions, and unfortunatelly these conditions go off when I put it in a small test file (you must know this Murphy law nightmare very well :-)).

I don't know if it is a gettext cache problem , but I haven't changed the translations. I tried the recommended nocache dir trick and I also tried to restart Apache (Apache/2.4.10 (Debian)), but it didn't help. My PHP version is 5.6.12-0+deb8u1.

How can this be non-deterministic? Where is the problem?

---

EDIT: encoding in /etc/php5/apache2/php.ini:

; PHP's default character set is set to UTF-8.
; http://php.net/default-charset
default_charset = "UTF-8"

; PHP internal character encoding is set to empty.
; If empty, default_charset is used.
; http://php.net/internal-encoding
;internal_encoding =

; PHP input character encoding is set to empty.
; If empty, default_charset is used.
; http://php.net/input-encoding
;input_encoding =

; PHP output character encoding is set to empty.
; If empty, default_charset is used.
; mbstring or iconv output handler is used.
; See also output_buffer.
; http://php.net/output-encoding
;output_encoding =

Answer 1

There was indeed a problem in the directory, because the code with __FILE__ was in different directory and I included it and didn't realize that the __FILE__ will then give wrong path. So I hardcoded the path instead:

bindtextdomain('messages', './lang/nocache'); # http://stackoverflow.com/a/13629035 
bindtextdomain('messages', './lang');

But what is really strange is that even with the wrong directory, it sometimes worked!!! This is really treacherous.